This invention relates to electrical stimulation apparatus and methods for use in stimulating body organs, and more particularly to implantable apparatus for stimulating neuromuscular tissue of the viscera of the organ structure, including the gastrointestinal tract and methods for installing the apparatus in a patient.
The field of electrical tissue stimulation has recently been expanded to include devices which electrically stimulate the stomach or intestinal tract with electrodes implanted in the tissue. These gastric stimulators have been found to successfully combat obesity in certain studies. Medical understanding as to how this treatment functions to reduce obesity is currently incomplete. However, patients successfully treated report achieving normal cycles of hunger and satiation. Some evidence supports the theory that food passes through the body quicker when the stimulation is occurring.
U.S. Pat. No. 5,836,994 to Bourgeois describes a laparoscopic device which has a needle which passes through the tissue being stimulated, and a thread attached at one end to the needle and at the other end to an implantable pulse generator (IPG) lead. The entire device can be inserted into the body via a laparoscopic type tube, or trocar, as it is relatively long and narrow. Many devices are known to be inserted through a trocar by having a needle attached with a thread to the devices.
Copending Cigaina U.S. application Ser. No. PCT/US98/1042 filed on May 21, 1998, and copending Cigaina U.S. application Ser. No. 09/122,832, filed Jul. 27, 1998, now U.S. Pat. No. 6,041,258 both of which are incorporated by reference in their entirety herein, describe a novel apparatus wherein the needle is incorporated into the end of the lead. Once the electrodes are inserted into the viscera, the electrodes are fixed in place by reverse angle tines.
A potential disadvantage of the above apparatus and methods of installation is that the electrodes must be affixed to the muscle of the stomach by actually imbedding the electrodes inside the tissue. Such a procedure may occasionally result in accidental deep perforation of the viscera. For example, the stomach muscle wall is generally less than 1 cm in depth, and the surgeon could easily puncture the inner wall of the stomach by angling his needle too deeply.
Thus, there is a need to provide an electrode apparatus that reduces the risk of injury to viscera tissue.
It is an advantage to provide an apparatus and methods of stimulation wherein the risk of injury to the viscera is reduced.
It is a further advantage of this invention is to allow the electrodes to interface the tissue on the outside surface of the viscera.
It is also an advantage of the invention to provide an apparatus and methods of stimulation wherein the electrodes may be implanted in a minimally invasive manner, such as laparoscopically.
It is a further advantage of the invention to provide an apparatus and methods of installing an electrode, wherein the electrode and any attachment means may be reduced in size to a compact form for installation into the patient""s body.
These and other objects of the invention are accomplished in accordance with the principles of the invention by providing apparatus and methods for installing such apparatus to the surface of neuromuscular tissue of the viscera, and particularly, the gastrointestinal tract. The apparatus includes at least two stimulating electrodes electrically connected to a pulse generator that supplies electrical stimulating pulses to the neuromuscular tissue. An electrode attachment member supports the electrodes, which may be embedded or otherwise attached to the electrode attachment member. The electrode attachment member has a distal surface configured for attachment to the surface of the neuromuscular tissue. The electrodes are at least partially exposed at the distal surface to provide an interface between the electrodes and the neuromuscular tissue.
In the most preferred embodiment, the electrode attachment member has a substantially flat distal surface fabricated from a flexible material. This flexibility allows the distal surface to substantially conform to any curvature of the neuromuscular surface. The flexibility also permits the electrode attachment member to be reduced in size to a compact form by rolling, folding, etc. The electrode attachment member may be inserted into the patient while in the compact form through minimally invasive laparoscopic or similar surgical access openings. A cylindrical sleeve member or annular bands may be provided to surround the electrode attachment member to assist in maintaining it in the compact form.
Preferred methods for installation in accordance with the invention include providing an electrode and an electrode attachment member which supports the electrodes adjacent a distal surface thereof. A further step may include providing a surgical access opening in the patient and laparoscopically introducing the electrode and the electrode attachment member into the patient. A subsequent step may include attaching the electrode attachment member to the surface of the neuromuscular tissue to provide an interface between the electrode and the tissue.
According to a preferred embodiment, the methods may also include partially compacting the electrode attachment member prior to laparoscopically introducing it into the patient. The compacting of the electrode attachment member may be performed by rolling or folding the member. The method may also include retaining the electrode attachment member in the compact form, such as, e.g., inserting it into an introduction sleeve or surrounding it with one or more annular bands.
After passing the electrode attachment member into the patient, the method may include returning the electrode attachment to its uncompacted form. If an introduction sleeve has been used, the method may include removing the electrode attachment member from the introduction sleeve. According to another preferred embodiment, the method may include severing the introduction sleeve or the bands and allowing the electrode attachment member to return to an uncompacted configuration. The method may include attaching the electrode attachment member to the neuromuscular tissue by stapling or suturing.
Although electrode attachment members in the form of a patch are described above, certain aspects of the invention are equally applicable to electrodes and electrode attachment members having other shapes and other methods of installation.
Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.